A conventional power conversion device includes: a capacitor series circuit which smooths DC voltage of a DC power supply circuit; and a power conversion section which converts the smoothed DC voltage into AC voltage by means of a semiconductor switching element. The conventional power conversion device also includes: a positive-electrode-side bus bar which connects the positive electrode of the capacitor series circuit and the positive electrode of the power conversion section; a negative-electrode-side bus bar which connects the negative electrode of the capacitor series circuit and the negative electrode of the power conversion section; and an intermediate connection bus bar which connects in series a first smoothing capacitor and a second smoothing capacitor. All the bus bars are formed so as to have substantially the same outer shape. In addition, the positive-electrode-side bus bar, the intermediate connection bus bar, and the negative-electrode-side bus bar are stacked with the intermediate connection bus bar interposed between the positive-electrode-side bus bar and the negative-electrode-side bus bar, thereby forming a three-layer structure. Accordingly, the current flows of adjacent bus bars are made opposite to each other, thereby allowing decrease of DC wiring inductances and reduction of spike voltage of the semiconductor switching element (see Patent Document 1, for example).